Such plastic (propellant) cartridges are used in firing devices, particularly a wide range of bolt guns. In this respect, the cartridges are mostly integrated into magazine strips (cartridge belt magazine). However, plastic cartridges can also be used in centrally firing weapons. The advantages of plastic cartridges are, in particular, the relatively low material and manufacturing costs and the cartridges can be manufactured by injection moulding. The initially described plastic cartridge and the initially described plastic cartridge belt magazine respectively are shown in DE 37 79 24 Al.
Plastic materials have substantially lower strength than metal, for example. Thus, with plastic materials, the problem of the extrusion of material occurs on account of the gas pressures arising during the combustion of the propellent or powder charge. Extrusion of material can occur wherever the breech of the firing device accommodating the cartridge and therefore the space surrounded by the cartridge recess and bottom of the breech, is not closed. Firing devices operated by means of a cartridge magazine strip have, for example, a breech which is not closed since the magazine strip is, in the region of its cartridge, accommodated directly by the cartridge recess, and is passed out from the cartridge recess on two sides of the breech, and indeed via narrow spaces between the cartridge recess and the bottom of the breech. Furthermore, cartridges, particularly plastic cartridges with flanges or the like leading out of the cartridge recess are intended to be provided with extensions in order to be able to grip (manually or mechanically) the cartridge for removal from the cartridge recess after ignition of the charge. The problem of the extrusion of material also occurs, in particular, with those firing devices in which the front end of the firing barrel is placed on the surface into which the bolt is to be driven, and the cartridge recess is thus pressed against the bottom of the breech (when the breech is unlocked).
With such easy-to-handle devices, incorrect operation can cause the firing pin to be triggered when the cartridge recess is not fully pressed against the bottom of the breech or the magazine strip, with the result that the lateral spaces are larger than technically required by the device.
In order to prevent extrusion of material in the known plastic cartridges, the cartridge body is designed with thick walls at its end on the cover side and therefore at its end lying against the bottom of the breech. The use of simpler and less strong plastics for cartridges therefore makes thicker-walled cartridge bodies necessary, at least in certain regions; this is problematical, not just on account of the space available for introducing the powder charge.